Flotation concentration of phosphatic material



Filed July 3.. 1928 W INVENTOR MW {Jab M4,

ATTORNEYS Patented Oct 28, 1930 UNITED STATES PATENT OFFICE 7 JOHN w. mrrnnrorm, or ALAMEDA, canronnm, ASSIGNOB TO mumps serm- TION NORTH AMERICAN conrona'rxomor NEW YORK, N. Y., A conrona'rxoiw or MARYLAND ILO'IATION CONCENTRATION OF PHbSPHATIC MATERIAL Application filed July 3, 192a. swarm. 290,284.

This invention relates to the concentration by flotation of phosphatic material and is herein illustrated as carried out in such apparatus as is often used for the froth-flotation concentration of ores, although under the present procedures often no froth is,

' formed of the usual type., The process is herein illustrated as. applied to the so-called phosphate rock of Florida and to the tailings residue or dbris from sieving processes of concentrating that material. The same procedures have been found useful with Tennessee phosphate rock.

It is known that the amount of the agents needed to effect the flotation of the phosphatic concentrate may be greatly reduced by elimination of the phosphatic and some othler slimes from the ground or fine materia It has now been found that the amount of the agents needed may be further diminished by so conducting the aerating agitation as to avoid as much as possible agitation in excess of that necessary to'raise the float concentrate. It has also now been found that the order of adding certain of'theagents. may be important in permitting the minimum amount of agent or agents to be effective. Under large-scale conditions, where the price of the available agents is of vital importance, best results with minimum consumption of agents have been obtained in the examples hereinafter given by adding caustic soda solution to a thick pulp in a screw conveyor serving as a preliminary mixer, and thereafter, during the IfllXlIlg, adding soap or a soap-forming material,

such for example, as oleic acid,and also adding, with the oleic acid or before or after adding the oleic acid, an agent commonly called a collector, such as fuel oil.

r The process has been found to work satisfactorily'in an apparatus such as is diagrammatically shown in the accompanying drawing, in which a pulp carrying about to deslimed solids, finer than I l-mesh, flows down a launder 1 into a screw conveyor 2 of an ordinary type having a trough 3, in which lies a revolving screw 4 so'that the to pulp flows along to a rotary pump 5, at the lower end of a conduit 6, by which pump the pulp is forced up through the conduit 6.

As the thick pulp flows along the mixer 2 it receives, first, a small amount of caustic soda 1n solution through a drip diagram-e cade froth-flotation cell 10 having a tank body 11, a pipe 12 through which the pulp falls on to a deflector 13 such as is shown in United States patent to Court No. 1,470,- 350, of October 9, 1923. The Cascadeflotation machine shown has three cells. As the pulp falls in the pipe 12 it gathers air which enters through inch openings 14 near the top of the pipe 12. The aerated pulp is deflected upwardly by the deflector 13 through an egg-crate baflie 15 above the deflector, and the float overflows past a lip 16 around the tank 11. A tailings discharge valve 17 is provided in the centerof the bottom of the tank 11 provided with a control handle 18, but there is also a weir-overflowtailings discharge 26 to determine the pulp level in relation to the overflow lip 16. The weir, in the form illustrated, is in the wall of a small separate compartment having a feed opening 27 admitting pulp from below the deflector 13 of the tank body 11 and open to the weir 26 over which the pulp flows into a tailings launder 28. The latter delivers the weir-overflow to a tailings discharge pipe 29 provided with air-admitting openings 8.

The overflowing float in the launder 19 aound the lip 16 runs down a launder 20 to a four cell subaeration froth-flotation machine 31 ofthe general type shown in the patent to Wilkinson and this applicant, No. 1,588,077, dated June 8th, 1926, where the float is cleaned by further flotation. As the float passes down the launder 20 it is joined be added in the pipe 12 by a valved supply 3 It is found that a much cleaner float 1S obtained if the cells include a doubly S10 (1 m baflle 24 around the sides below the over ow lip, forming -a constriction so that the float rises near the center of the cell and flows over a uiet zone above the baflle 24 because that ba e keeps rising material away from thelip. It is also found advantageous to enclose the central third, or so, of the cells 11, 22 and 23 with baflies 30 which prevent surgings of the ulp from reaching their overflow lips 16.

The cells of the four-cell subaeration machine 21 are found to deliver a cleaner float if provided with paddles 31 for assisting the prompt overflow of 'the float concentrate. The tailings from the machine 21 form a middling which is returned to the pump 5.

In the devices just described the thick pulp Mud of deslimed crudephosphatic material is gently but thoroughly mixed, first with the caustic alkali, then with the red oil and fuel oil, and the pulp is then thinned and concentrated by flotation with a minimum of agitation. By this procedure the usually muddy mill water absorbs, a minimum quantity of the added agents, yet the phosphatic material is adequately treated with the agents.

It does not appear to be necessary that the caustic soda remain in the pulp water. Useful results were obtained when the pulp water was drained off after adding the caustic soda, the solids cautiously washed, and then made into a pulp with water and floated with the aid of oleic acid. It has also been found possible to obtain useful results by adding a less amount of caustic soda as a first addition to the thick pulp, following this withthe addition of an oleic acid soap instead of red 01 It has been found that the cost of agents consumed in the foregoing procedures is about one fourth of the cost of the agents consumed in procedures hitherto used.

Example 1.In one laboratory test run tailings from a concentration 0 eration effected by screening Mulberry, F orida, rock, 'finer than 20-mesh and deslimed, were gently stirred by hand as a thick pulp containing 7 0% solids with 0.5 pounds of caustic soda added in solution. Then there was added 0.72 pounds per ton of oleic acid during the continuance of the stirring, followed by 4.0 pounds of fuel oil, all per ton of dry material. The resulting pulp was then thinnedto about 4 to 1 with mine water, containing the usual slimes, and agitated in a laboratory froth-flotation spitzkasten sub-aeration machine and the float removed for threeniinutes. The results are shown in the following table in which B. P. L. represents bone phosphate of lime:

Peru's! Exam le 2.In another test clear Long Island ity, N. Y., tap water was used in the same procedure, except that the added agents were used in less quantity, viz, 0.4 pounds of caustic soda, 0.56 ounds of oleic acid, and 1.68 ounds of fue oil all per ton of solids. The rst concentrate was cleaned, yielding a finished concentrate and a middlin The results are shown in the following ta le:

wt. 13. P. L. mm

m: Per m: 32.2 100 11.2 cu 14.4 4.0 4. 0 6. 3

The foregoin test shows a further reduced consumption 0 agents.

Ea'ample 3.On a large scale test rurrin which about 20 tons of concentrates were obtained in seven hours, treatin tailings of the same character, but only art v deslimed, the apparatus shown in the rawin was used in the manner above described. T e caustic solution was added at the rate of 0.3 pounds of the dry causticper' ton of solids. There was also added 0.7 pounds of oleic acid and 3.0 pounds of fuel oil, both per ton of solids.

here was also added at the subaeration cells 21 of the accompanying drawing, 0.15 pounds of steam-distilled pine oil per ton of solids in the ori inal feed. The results are shown in the folTowing table, the higher bone phosphate of lime content of tailin being due to the deleterious action of the simes present:

Per cent Per cent 29. 78 100 Conn 71. 89 M. 1 TAIL! 1L (8 36. 9

procedure of the first of the foregoing tests M1 was used, save that 0.8 ounds of caustic soda 0.9 pounds of oleic acld, and 6.0

pounds 0 fuel oil were used r ton of solids, and there was further adde in the flotation machine 0.15 pounds per ton of steam distilled pine oil.

The results are shown in the following table:

Recover- Wt. .B. P. L. is

Per cent Per cent Per cent Heads 100 3t 77 100 Cones 43. 5 73. 6 93. 2 afls 5B. 6 4. 3 6. 8

Example 5.A arallel test in the absence of pine oil yielde the following results:

In other tests a soap solution was added instead of oleic acid. I I

E sample 6.In one such test phosphatic material of the same kind was made into a thick pulp with Long Island Cit tap water, and to this was added 0.2 poun of caustic soda per ton, and then 1.4 pounds of soap per ton, containing 1.2 pounds oleic acidper ton. There was also added 1.68 pounds per tonof fuel oil. The pulp was then thinned to about a 4 to 1 pulp with the same water and a float concentrate obtained in the testing machine and then recleaned in the same machine to yield a finished concentrate and a middling. The results are shown in the following table:

Recover- Wt. B. P. L. 188

Per cent Per cent Per cent Heads 100 31. 4 100 Example 7.-Results seem to be little afi'ected by the method of adding the fuel oil. In one test the same procedures were used except that 0.6 pounds of caustic soda were used and 0.8 pounds of oleic acid were used in admixture with 6 pounds of fuel oil, all per ton of solids. The pulp was then thinned to about a 4-. to 1 pulp with the same water and a float concentrate obtained in the testing machine and then recleaned in the same machine slimes with alkali, thereafter mixing it with from slimes with caustic soda, thereafter The results are Shown in the following table:

Recoverwt. I

. 2.7 Tails 9. 3

Having thus described certain embodiments of my invention what I claim is:

1. The process of concentrating phosphatebearing material which consists in mixing'a pulp of the material relativel free from a float-assisting substance, a 'tating to proguce a float concentrate, an separating the cat, I

2. The process of concentrating phosphate- 1 bearing material which consists in mixin a thick pulp of the material relatively ree from slimes with caustic soda, thereafter mixing it with a float-assistin substance, thirmihg the pulp, agitating the tiinned pulp to produce a float concentrate, and separating the float.

3. The process of concentrating phosphatebearing material which consists in mixing a thick pulp of the material relatively free mixing it with a float-assisting substance thinning the pulp. subjecting the thinne pulp to a cascade flotation o eration to progucg a float concentrate, an separating the ca 4.. The process of concentrating phosphatebearing material which consists in mixing a pulp of the material relatively free from slimes with alkali, thereafter mixing it with a'soapfo'rming substance, a 'tating to progucg .a float concentrate, an separating-the 5'. The process of concentrating phosphatebearing material which consists in fnixing'a thick pul of the material relatively free from slimes wlth caustic soda, thereafter mixing it with a soap forming substance, thinning the pulp, agitating the thinned pulp to proguce a float concentrate, and separating the 6. The process of concentrating phosphatebearing material which consists in mixing a thick pulp of the material relatively free from slimescwith caustic soda, thereafter mixing it with a soap-forming substance, thinning the pulp, subjecting the thinned pulpto a cascade flotation operation to proguce a float concentrate, and separating the cat.

7. The process of concentrating phosphate- Pcr cm bearing material which consists in mixing a to yield a finished concentrate and a middling. a float-assisting material containing a soap- I formingagitating to roduce a float concentrate, and-separating t e float. 8. The process of concentratingphosphate- :bearing material which consists in a thick ulp of the material relatively me from s imes with caustic soda, thereafter mix- I ing it with'a float-assisting material opntain- I thick v tion to 'roduce'a float concentrate and separating a float.

10. The process of concentrating phoshate-bearing material which consists in mixmg a pul of the material relatively free from new hatebearing material which consists in mixing a pulp of the material relatively free from slimes with alkali, thereafter mixing with a float-assisting substance, agitating so as to produce a float concentrate in the substantial absence of-excess agitation, and rapidly ning the pulp, a 'tating the thinned pulp in the substantial a flowing the float.

In testimon whereof, I have aflixed m signature to t is s ification.

J O N W. LITTLEFORD.

slimes with-alkali, thereafter mixm it with oleic acid, 'tating to produce a oat concentrate, an separating the float.

11. The process of concentrating phosphate-bearin material which consists in mix-ing a thic pulp of the material relatively free from slimes with caustic soda, thereafter mixing it with oleic acid, thinning the pulp, agitating the thinned pulp to roduce a float concentrate, and separating t e float.

12. The process of concentrating phosphate-bearing material which consists in mixing a thick pulp of the material relatively free from slimes with caustic soda, thereafter mixing it with oleic acid, thinning the pulp, subjecting the thinned pulp to a cascade flotation operation to produce a float concentrate and separating the float.

13. The process of concentrating phoshate-bearing material which consists in mixmg a pulp of the material relatively free from slimes with alkali, thereafter mixing it with oleic acid and an unsaponifiable oil, agitating to produce a float concentrate, and separating the float. I

14. The process of concentrating phosphate-bearing material which consists in mixmg a thick pulp of the material relatively free from slime with caustic soda, thereafter mixing it with oleic acid and an unsaponifiable oil, thinning the pul agitating the thinned pulp to roduce a float concentrate, and separating t e float.

15. The process of concentrating phosphate-bear' material which consists in mixing a thick pu p of the material relatively free from slimes with caustic soda, thereafter mixing it with oleic acid and an unsaponi-- fiable oil, thinning the pulp, subjecting the thinned pulp to acascade flotation operation to produce a float concentrate, and separating the float.

16. The process of concentrating phosnce of excess agitation to produce a float concentrate, and rapidly over- 

